Effects Of Chromatic Adaptation Research Articles

CVD-MET: an image difference metric designed for analysis of color vision deficiency aids.

Color vision deficiency (CVD) has gained in relevance in the last decade, with a surge of proposals for aid systems that aim to improve the color discrimination capabilities of CVD subjects. This paper focuses on the proposal of a new metric called CVD-MET, that can evaluate the efficiency and naturalness of these systems through a set of images using a simulation of the subject's vision. In the simulation, the effect of chromatic adaptation is introduced via CIECAM02, which is relevant for the evaluation of passive aids (color filters). To demonstrate the potential of the CVD-MET, an evaluation of a representative set of passive and active aids is carried out both with conventional image quality metrics and with CVD-MET. The results suggest that the active aids (recoloration algorithms) are in general more efficient and produce more natural images, although the changes that are introduced do not shift the CVD's perception of the scene towards the normal observer's perception.

Chromatic adaptation in a 2D photograph demonstrated by a D‐up viewer

AbstractIt is said that we cannot have color constancy in a photograph. The concept of recognized visual space of illumination (RVSI) asserts that chromatic adaptation occurs when one perceives the illumination that is filling a space and not the objects in the space. It predicts then that if one perceives a 3D scene in a photograph, then color constancy will occur in the photograph. In this work, a dimension‐up (D‐up) viewer was developed to perceive a 3D scene on a 2D photograph, and the effect of chromatic adaptation was measured by the color appearance of a gray patch placed at the center of the photograph. Subjects saw the patch as a vivid color when they saw a photograph that had been taken under colored illumination, which is a normal experience in a real space observation. When the color appearance was measured by the elementary color naming method, the amount of chromaticness of the patch in percentage and the apparent hue were very similar to those observed in the 2‐room technique, thus confirming the prediction by the RVSI theory.

Radiometric Compensation of Images Projected on Non-White Surfaces by Exploiting Chromatic Adaptation and Perceptual Anchoring.

Flat surfaces in our living environment to be used as replacements of a projection screen are not necessarily white. We propose a perceptual radiometric compensation method to counteract the effect of color projection surfaces on image appearance. It reduces color clipping while preserving the hue and brightness of images based on the anchoring property of human visual system. In addition, it considers the effect of chromatic adaptation on perceptual image quality and fixes the color distortion caused by non-white projection surfaces by properly shifting the color of the image pixels toward the complementary color of the projection surface. User ratings show that our method outperforms the existing methods in 974 out of 1020 subjective tests.

Modelling the effects of chromatic adaptation on phytoplankton community structure in the oligotrophic ocean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 406:1-17 (2010) - DOI: https://doi.org/10.3354/meps08588 FEATURE ARTICLE Modelling the effects of chromatic adaptation on phytoplankton community structure in the oligotrophic ocean A. E. Hickman1,2,*, S. Dutkiewicz2, R. G. Williams1, M. J. Follows2 1Department of Ocean and Earth Sciences, University of Liverpool, Liverpool L69 3GP, UK 2Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 01239, USA *Email: ahickman@liv.ac.uk ABSTRACT: We explored the role of chromatic adaptation in shaping vertical phytoplankton community structures using a trait-based ecosystem model. The model included 1000 ‘phytoplankton types’ and was applied to the oligotrophic South Atlantic Gyre in a 1-dimensional framework, where ‘phytoplankton types’ refers to the model phytoplankton that were stochastically assigned unique physiological characteristics. The model incorporates multi-spectral optics and light absorption properties for the different phytoplankton. The model successfully reproduced observed vertical gradients in the nitrate, bulk phytoplankton properties and community structure. Model phytoplankton types with Synechococcus-like spectral light absorption properties were outcompeted at depth, where eukaryote-like spectral properties were advantageous. In contrast, photoinhibition was important for vertical separation of high-light and low-light Prochlorococcus model analogues. In addition, temperature dependence was important for selection of phytoplankton types on the temperature gradient. The fittest, or successful, phytoplankton types were characterised by combinations of simultaneously optimal traits that suited them to a particular depth in the water column, reflecting the view that phytoplankton have co-evolved multiple traits that are advantageous in a particular environmental condition or niche. KEY WORDS: Phytoplankton · Chromatic adaptation · Photosynthesis · Niche · Modelling · Species · Selection · Pigments Full text in pdf format Information about this Feature Article NextCite this article as: Hickman AE, Dutkiewicz S, Williams RG, Follows MJ (2010) Modelling the effects of chromatic adaptation on phytoplankton community structure in the oligotrophic ocean. Mar Ecol Prog Ser 406:1-17. https://doi.org/10.3354/meps08588 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 406. Online publication date: May 10, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

Development of chromatic adaptation transforms and concept for their classification

AbstractThree types of international recommendations are necessary on CATs (chromatic adaptation transforms). CAT‐Type I and CAT‐Type II are for general use on chromatic adaptation studies. The former is related to chromatic adaptation theory and the latter to performance on field trial data. In addition, CAT‐Type III is necessary for a specific and practical purposes. The need for classifying to CAT‐Type I and CAT‐Type II is found from a careful inspection of the development process from Nayatani et al. transform to BFD transform, referring to the Ph. D. thesis by Lam (University of Bradford, 1985). The process clearly shows two types of flows on the development of various CATs. One is the flow for deepening the theory of chromatic adaptation (CAT‐Type I), and the other is for giving good performance to existing field trial data and also ease of use (CAT‐Type II). Additional CAT‐Type III is, for example, CAT recommended in CIE TC 8‐04 technical report. The CAT is only applicable to compare hardcopy and softcopy images for the specified observing conditions in the report. Still, a difficult problem, determination of corresponding colors, remains in the method of subjective estimation, which is useful and widely used for estimating chromatic adaptation effects experimentally. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 205–217, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20210

Positional adaptation reveals multiple chromatic mechanisms in human vision.

Precortical color vision is mediated by three independent opponent or cardinal mechanisms that linearly combine receptoral outputs to form L/M, S/(L+M), and L+M channels. However, data from a variety of psychophysical and physiological experiments indicate that chromatic processing undergoes a reorganization away from the basic opponent model. Frequently, this post-opponent reorganization is viewed in terms of the generation of multiple "higher order" chromatic mechanisms, tuned to a wide variety of axes in color space. Moreover, adaptation experiments have revealed that the synthesis of these mechanisms occurs at a level in the cortex following the binocular integration of the inputs from each eye. Here we report results from an experiment in which the influence of chromatic adaptation on the perceived visual location of a test stimulus was explored using a Vernier alignment task. The results indicate that not only is positional information processed independently within the L/M, S/(L+M), and L+M channels, but that when adapting and test stimuli are extended to non-cardinal axes, the existence of multiple chromatically tuned mechanisms is revealed. Most importantly, the effects of chromatic adaptation on this task exhibit little interocular transfer and have rapid decay rates, consistent with chromatic as opposed to contrast adaptation. These findings suggest that the reorganization of chromatic processing may take place earlier in the visual pathway than previously thought.

Effects of chromatic adaptation on relation between the cone mechanisms and the red-green color opponent system

Effects of chromatic adaptation on relation between the cone mechanisms and the red-green color opponent system

Chromatic adaptation alters spectral sensitivity at high temporal frequencies

To evaluate the effects of chromatic adaptation on spectral sensitivity at temporal frequencies within the region of high-frequency linearity, critical flicker frequency was measured as a function of red-green luminance ratio for counterphase flicker of 649- and 555-nm light. For eight observers, the relative weight of the contribution of the long-wavelength-sensitive cones to flicker detection was smaller on long-wavelength adapting fields than on middle-wavelength adapting fields even though long-wavelength-sensitive-cone modulations were high. These data indicate that chromatic adaptation can confound the interpretation of flicker-sensitivity data that are gathered with long-wavelength test lights or with equiluminant heterochromatic flicker and that there can be considerable interobserver variability in the effects of chromatic adaptation.

Effect of Color on Contrast Sensitivity with Two Different Accommodative Stimuli

We studied the influence of color and accommodation on the contrast sensitivity function (CSF). At the same time, we measured the effect of axial chromatic aberration (ACA) on the CSF. The CSF's of two observers were determined using red, green, blue, and white light, at 5- and 0.5-m viewing distances. At 5 m the CSF's were measured with natural vision and also with lenses which compensated the ACA. Results show that the effect of ACA on the CSF is to reduce the sensitivity to blue with respect to the red. The difference in sensitivity between these two colors is between 50 and 150% and varies with the frequency and the subject. When the ACA is compensated the influence of the color on the CSF is very small, in our experiment, and this result is discussed in relation to the compensating effects of chromatic adaptation of the color mechanisms. In near vision, the CSF's were measured with natural vision and also with the lenses required to give the same accommodative stimulus for all colors. We discuss the effect of accommodation on the CSF. For both far and near the results are compared with the CSF with white light.

Spectral properties of short-wavelength (blue) cones in the turtle retina

Long- and medium-wavelength cones in the turtle retina participate in complex neural interactions. They are coupled via excitatory pathways to other cones and receive negative feedback inputs from luminosity-type horizontal cells. Little information has been collected on the S- (short-wavelength or blue) cones because they are scarce in the turtle retina and of smaller dimensions compared to the other cone types. In this paper, flash sensitivity action spectra and photoresponses of seven turtle S-cones were measured in the dark-adapted state and during chromatic background illuminations. The desensitizing action of monochromatic background lights was not uniform across the visible spectrum. A red background was most effective in desensitizing the S-cones to long-wavelength stimuli while a blue background light produced its strongest action on the photoresponses elicited by short-wavelength stimuli. The effects of chromatic adaptation on the S-cone action spectrum and on the kinetics of the small-amplitude photoresponses suggested that the S-cones in the turtle retina were involved in complex neural interactions. These included excitatory inputs probably originating in neighboring L-cones and inhibitory long-wavelength inputs probably mediated by L-type horizontal cells.

Effects of chromatic adaptation on opponent interactions in monkey increment-threshold spectral-sensitivity functions

The effects of chromatic adaptation on the opponent interactions of cone mechanisms were investigated by using increment-threshold spectral-sensitivity (ITSS) functions and threshold-versus-radiance (TVR) curves in rhesus monkey subjects. The TVR curves showed shape- and field-sensitivity invariance for both 580- and 500-nm adapting backgrounds and indicated that three cone mechanisms were mediating detection over moderate adapting-field intensity levels. Differential adaptation between the long-wavelength-sensitive (L) and the middle-wavelength-sensitive (M) opponent (L - M) and nonopponent (L + M) channels and the short-wavelength-sensitive (S) channel caused changes in the shape of the ITSS function as the adapting-field intensity was increased without changes in the level of cone interaction. Chromatic adaptation also resulted in significant changes in the shape of the ITSS functions, but it still exhibited characteristic L-M opponent interactions. Converting ITSS data to cone-contrast coordinates for R-G adapting fields indicated that the relative contribution of the L and M cones at the second site was approximately equal (detection contour slope approximately 1). Consequently, most of the changes in the shape of ITSS functions under chromatic adaptation are explained by the von Kries adaptation principle. ITSS functions on a green background also exhibited opponent interactions between S cones and longer-wavelength cones. The cone-contrast coordinates, when expressed for S cones, showed that the inhibitory interactions occur because the S-cone signal subtracts from both M and L cones.

Simulated bipolar cells in fovea of human retina

Effects of chromatic adaptation on C-type bipolar cells (BC) in human retinal fovea are studied. Adaptation of the r-g channel is linear for both central fovea and parafovea. Adaptation of the parafovea bl-y channel, on the other hand, is nonlinear, which is accounted for by the slower adaptation rate of blue-sensitive cones with white light intensity as compared to rates of red- and green-sensitive cones. Achromatic adaptation of red- and green-center BCs produces uniform response decreases but without unique yellow loci shifts. Achromatic adaptation of blue-center BCs, on the other hand, does cause shifts of the unique green locus. Shifts of the crossover points for the BC response spectra occur with chromatic adaptation; the unique yellow loci shifts to shorter wavelengths with adapting wavelengths shorter than 550 nm and longer wave-lengths with longer adapting wavelengths than 550 nm. Chromatic adaptation is sufficient to explain the Bezold-Brüke effects; but to fully account for these shifts a novel hypothesis is proposed. For the green and red spectrum regions Bezold-Brücke shifts are due to r-g channel chromatic adaptation, while for the blue spectrum region bl-y channel chromatic adaptation accounts for Bezold-Brücke shifts. The two channels function independently in an either/or manner. The bl-y channel, besides having a unique green locus at 517.7 nm, has a crossover point at about 670 nm. Chromatic adaptation of the bl-y channel produces shifts of the unique red locus, which may account for extraspectral hue shifts.

Simulated bipolar cells in fovea of human retina

A computer model of simulated bipolar cells (BC) in the human retina is used to study wavelength discrimination (lambda delta). lambda delta curves are obtained for the two C-types of BCs in the central fovea and the three C-type BCs of the parafovea under various conditions. For the parafovea algebraic addition of the three C-type BCs with proper weighting of the blue-center BC, such that the unique orange locus = 600 nm, gives a combined channel whose lambda delta curve agrees remarkably well with those found in the literature based on human and primate psychophysics. Other studies include effects of chromatic adaptation and dispersion on lambda delta. From this and earlier studies it can be concluded that the center/surround organization of the BCs optimize resolution in the presence of natural occurring dispersion; in addition a specific BC receptive field organization could be picked as being optimal.

Model for color vision and light adaptation

A multizone color model is described. It has nonlinear receptor gain control, two postreceptor opponent-colors processing stages, and neural compression late in the visual pathway. It is assumed that gain control can be activated by receptor responses from a test light itself (self-adaptation) and (or) by receptor responses from other adapting fields. Apparent brightnesses and visual discriminations are mediated by the first processing stage, and apparent hues and saturations are mediated by the second stage. The model accounts for a wide range of data, including nonlinear hue shifts in the color solid, various apparent brightness effects, visual discriminations for achromatic and chromatic lights under various adaptation conditions, and effects of chromatic adaptation on color appearances.

Chromatic adaptation on the minimally distinct border and brightness matching in color‐normals and deuteranopes

AbstractWe examined the effect of monochromatic adapting lights on minimally distinct border (MDB) settings and brightness matching (BM) between monochromatic test and reference fields by using three color‐normals and three deuteranopes as observers. In the case of MDB, for color‐normal observers chromatic adaptation appeared prominetly in the wavelength regions near the test and reference wavelengths in the corresponding field, when either the test or reference field was in the long‐wavelenth region. No differential effect was found for deuteranopic observers. Using BM instead of MDB, the differential effects of chromatic adaptation appeared more prominently in the short‐wavelength region for both types of observers (especially for color‐normals) and in the middle‐wavelength region for color‐normal observers. The results indicate that the blue‐sen‐sitive mechanisms make either little or no contribution to the MDB criterion, or the distinctness of borders.

Throwing Light on Metamerism: Quantifying the Change in a Colour Match Caused by Change of Illuminant

The article discusses the concept of illuminant metamerism, which is the phenomenon that occurs when two coloured surfaces match under one illuminant but not under another. Quantifying this effect is important commercially, and the convention for measuring it is referred to as a metameric index. The metameric indices could be more useful if they included the effect of chromatic adaptation by the observer.

Effects of chromatic adaptation on phase-dependent sensitivity to heterochromatic flicker.

Temporal modulation sensitivity was measured as a function of the relative phase of two equiluminous chromatic sources (564 and 625 nm) for temporal frequencies from 6 to 20 Hz. The difference between 180 degrees and the phase of least sensitivity was computed as the measured phase shift. A 2 degree test field was superimposed upon 8 degrees chromatic adapting fields with luminances from 100 to 3000 Td and chromaticities of 500, 600, and 650 nm. For each adapting field, the 564-nm source was set to 175 Td, and the 625-nm source was matched to it with heterochromatic flicker photometry (giving an effective mean luminance of 350 Td). The 650-nm adapting fields produced large changes in photometric setting but only small changes in the measured phase shift. The 600- and 500-nm adapting fields produced smaller changes in photometric setting but larger changes in the measured phase shift. In general, increased adapting luminance resulted in an increase in the measured phase shift for 600-nm adaptation and a decrease in the measured phase shift for 500-nm adaptation.

Field trials on color appearance of chromatic colors under various light sources

AbstractField trials of the nonlinear color‐appearance model and the nonlinear chromatic‐adaptation transform were done on the effect of chromatic adaptation between illuminants C and A, and also on the visual estimations by Mori and Fuchida under five fluorescent lamps. The model could give reasonably good predictions to the visual estimations in the above two conditions. In addition, the present study confirmed that the nonlinear color‐appearance model and the nonlinear chromatic‐adaptation transform could better predict the chromatic‐adaptation effect between C and A than the von Kries law.

Exhibiting artwork: Consider the illuminating source

AbstractThis article describes the steps that should be considered for the proper illumination of artwork. In particular, our intent is to show how a different illuminating environment from one intended by the artist affects the color appearance of exhibited paintings. Using five different illuminants and several illumination levels, it is shown for eight artists' pigments that large color‐appearance differences occur. This is true even after the effects of chromatic adaptation are taken into account.

A FORTRAN program for predicting the effects of chromatic adaptation on color appearance based on current CIE recommendations

AbstractThe CIE has recently recommended for field trial a method for predicting corresponding colors with a change in chromatic adaptation. To aid the CIE in collecting results illustrating the accuracy of these predictions, a FORTRAN program currently used by the Munsell Color Science Laboratory is listed along with test data. This chromatic‐adaptation transform can be used to calculate CIELAB or CIELUV metrics for non‐daylight illuminants, indices of illuminant metamerism, and indices of color constancy. Including this transform in these calculations, it is hoped, will result in metrics with better correlation to visual assessments. It is hoped that readers will implement this method, compare the effectivness of this chromatic‐adaptation transform to visual evaluations, and report their results to CIE Technical Committee 1–06.